linux-kernel - Re: [PATCH v17] exec: Fix dead-lock in de_thread with ptrace

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Message-ID: <20251102161712.GA4273@redhat.com>
Date: Sun, 2 Nov 2025 17:17:12 +0100
From: Oleg Nesterov <oleg@...hat.com>
To: Bernd Edlinger <bernd.edlinger@...mail.de>
Cc: Alexander Viro <viro@...iv.linux.org.uk>,
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Subject: Re: [PATCH v17] exec: Fix dead-lock in de_thread with ptrace_attach

On 08/21, Bernd Edlinger wrote:
>
> v16: rebased to 6.17-rc2, fixed some minor merge conflicts.
>
> v17: avoid use of task->in_execve in ptrace_attach.

So I guess this version doesn't really differ from v14 I tried to review...
(yes, iirc my review wasn't really good, sorry).

Perhaps I am wrong, but I still think we need another approach. de_thread()
should not wait until all sub-threads are reaped, it should drop cred_guard_mutex
earlier.

I mean, something like

	[PATCH V2 1/2] exec: don't wait for zombie threads with cred_guard_mutex held
	https://lore.kernel.org/lkml/20170213180454.GA2858@redhat.com/

which is hopelessly outdated now.

Again, perhaps I am wrong. I'll try to take another look next week.

Oleg.